Network aided terrestrial triangulation using stars (NATTS)

ABSTRACT

A method for determining a terrestrial location of an apparatus that is deployed in a generally known geographical region includes capturing, by the apparatus, an earthbound image of the sky from a terrestrial location at an identified time; communicating, by the apparatus, data representative of the captured earthbound image of the sky; and determining the terrestrial location of the apparatus based on the data communicated by the apparatus by comparing the captured earthbound image of the sky to a master mapping of the sky relative to the surface of the Earth.

I. CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a nonprovisional of, and claims priorityunder 35 U.S.C. § 119(e) to Twitchell, U.S. Provisional PatentApplication No. 60/687,073 filed Jun. 3, 2005. The entire disclosure ofthis patent application is hereby incorporated herein by reference.

II. INCORPORATION BY REFERENCE

The present application hereby incorporates by reference: Twitchell U.S.Pat. No. 6,934,540 titled “Network Formation in Asset-Tracking SystemBased on Asset Class”; Twitchell U.S. Pat. No. 6,745,027 titled “ClassSwitched Networks for Tracking Articles”; Twitchell U.S. PatentApplication Publication No. 20060018274 titled “Communications withinPopulation of Wireless Transceivers Based on Common Designation”; andTwitchell U.S. Patent Application Publication No. 20050215280 titled“LPRF Device Wake Up Using Wireless Tag.”

III. COPYRIGHT STATEMENT

All of the material in this patent document is subject to copyrightprotection under the copyright laws of the United States and othercountries. The copyright owner has no objection to the facsimilereproduction by anyone of the patent document or the patent disclosure,as it appears in official governmental records but, otherwise, all othercopyright rights whatsoever are reserved.

IV. BACKGROUND OF THE INVENTION

Determining the positions of remote communications devices and assets towhich they may be attached is a critical challenge for which previouslyavailable solutions are increasingly inadequate. For example, when aremote communications device is in communication with a Wide AreaNetwork (WAN) transmitter, location of the communications device on amacro scale is available by way of knowledge of both the position of theWAN transmitter and the maximum effective range of the communication.

Techniques for determining more precisely the location of an asset areavailable. Such techniques involve determining Time of Arrival (TOA) andTime Difference of Arrival (TDOA) of radio frequency (RF) signals todeduce distances between wireless devices. In addition, determinationsof Angle of Arrival (AOA) are utilized to deduce directions of signals.Global Positioning System (GPS) technology is also available fordetermining, with relatively high precision, the locations of assetsequipped with specialized receivers that measure time travel of radiosignals from satellites. However, these known technologies arevulnerable in that electronic signal jamming technologies are capable ofblocking wireless signals to deny the ability to locate assets.Accordingly, a method of determining the location of a communicationsdevice that is not susceptible to jamming technologies is needed.

Celestial navigation is a position fixing technique that was the firstsystem devised to help sailors locate themselves on a featureless ocean.Celestial navigation uses angular measurements, i.e., sights, betweenthe horizon and a common celestial object. The Sun is most oftenmeasured. Skilled navigators can use the Moon, planets or one of the 57“navigational stars” that are described in nautical almanacs. Sights onthe moon, planet and stars allow navigation to occur at night or whenclouds obscure other objects.

Celestial navigation works because at any given instant of time, anyparticular celestial object will be directly over a particulargeographic position on the Earth, i.e., it will have an exact latitudeand longitude. The actual angle to the celestial object locates thenavigator on a circle on the surface of the Earth. Every location on thecircle has the same angle to the celestial object. The circle will becentered on the celestial object's latitude and longitude. Two or threesights on different objects, or at different times, establish that thenavigator is at the intersection of several such circles. The sights arereduced to positions by simple methods that add and subtract logarithmsof trigonometric values taken from tables.

Practical celestial navigation usually requires a chronometer to measuretime, a sextant to measure the angles, an almanac giving angularschedules of celestial objects, a set of sight reduction tables to helpperform the math, and a chart of the region. With sight reductiontables, the only math required is addition and subtraction. Smallhandheld computers and laptops enable modern navigators to “reduce”sextant sights in minutes, by automating all the calculation and datalookup steps.

Celestial navigation is not dependent on receipt of RF signals.Therefore, it would be advantageous to be able to use the basictechniques of celestial navigation to determine the location of remotecommunications devices.

V. SUMMARY OF THE INVENTION

The present invention includes many aspects and features.

In an aspect of the invention, an apparatus comprises an imagingcomponent configured to capture an earthbound image of the sky from aterrestrial location, a chronometric component that measures timesynchronously with standard time, and a communication componentconfigured to wirelessly transmit data representative of a capturedearthbound image of the sky. Preferably the chronometric component is aclock that accurately measures time. Standard time is the official timein a local region, adjusted for location around the Earth and isestablished by law or custom. Accordingly, the chronometric component ofthe apparatus measures time in synchrony with standard time. Theapparatus also comprises a controller that is arranged in electroniccommunication with the imaging component, the chronometric component,and the communication component. The controller is configured to causean earthbound image of the sky to be captured using the imagingcomponent at a time identified by the chronometric component and datarepresentative of the captured earthbound image to be wirelesslytransmitted. With regard to the controller, it is preferred thatconfigured means programmed.

In a feature of the aspect, the controller is further configured tocause data representative of the identified time that the earthboundimage of the sky is captured to be wirelessly transmitted in conjunctionwith the transmission of the data representative of the captured image.

In another feature of the aspect, the apparatus further comprises aninternal power supply for powering of the imaging component, thechronometric component, the communication component, and the controller.Further, the controller comprises a microcontroller. In yet anotherfeature, the controller comprises a microprocessor.

In an additional feature, the controller is configured to cause, inresponse to the occurrence of a predetermined event, an earthbound imageof the sky to be captured using the imaging component, the time at whichthe earthbound image was captured to be identified using thechronometric component, and data representative of the capturedearthbound image and identified time to be wirelessly transmitted. In afurther feature of this aspect, the controller is configured to cause,in response to the expiration of a predetermined period of time, anearthbound image of the sky to be captured using the imaging component,and data representative of the captured earthbound image to bewirelessly transmitted.

In still yet another feature, the apparatus further comprises a receiverfor receiving wireless communications. In accordance with this feature,the controller is configured to cause, in response to an instructionwirelessly received in a communication by the receiver, an earthboundimage of the sky to be captured using the imaging component, the time atwhich the earthbound image was captured to be identified using thechronometric component, and data representative of the capturedearthbound image and identified time to be wirelessly transmitted.

In an additional feature, the imaging component comprises acharge-coupled device (CCD). In accordance with this feature, the CCDcollects electromagnetic radiation at wavelengths below 2000 Angstroms.In furtherance of this feature, the CCD collects electromagneticradiation at wavelengths above 7000 Angstroms. In another feature, theimaging component is configured to process a captured earthbound imageof the sky. It is preferred that the processing comprises homomorphicfiltering. The image may include the sun and/or other stars; the moon;and/or other celestial bodies in the sky.

In a further feature, the imaging component is configured to capture anearthbound image of the sky at night. In another feature of this aspect,the apparatus comprises an accelerometer. With regard to this feature,the apparatus further comprises a compass, wherein the apparatus ismobile and wherein the controller is arranged in electroniccommunication with the accelerometer and the compass and is configuredto cause data representative of movement of the apparatus to bewirelessly transmitted in conjunction with the transmission of the datarepresentative of the captured earthbound image. It is preferred thatthe compass is a gyrocompass.

In another feature, the imaging component is configured to capture anearthbound image of the sky during daylight hours. In accordance withthis feature, the controller is configured to cause a plurality ofearthbound images of the sky to be captured using the imaging componentat time intervals that are identified by the chronometric component, andis configured to cause data representative of the captured earthboundimages to be wirelessly transmitted.

In still yet another feature, the apparatus is associated with an assetthat is deployed within a generally known geographical region. An assetcomprises a person or thing that is desired to be tracked or monitored.With respect to a person, an asset may be an employee, a team member, alaw enforcement officer, or a member of the military. With respect to athing or article, an asset may be, for example, a good, product,package, item, vehicle, warehoused material, baggage, passenger,luggage, shipping container, belonging, commodity, effect, resource,merchandise or sensor. It is preferred that the asset comprises asensor. Although the exact location of the asset is unknown, a generallocation of the asset within a geographic region is known. For example,the country within which the asset is located is known.

In furtherance of this feature, the apparatus comprises a node of aremote sensor interface (RSI) network. An RSI network as used herein andin some of the incorporated references represents a network, nodes ofwhich (and specifically, the data communications devices of the nodes ofwhich) each are disposed in electronic communication with one or moresensors for acquiring data there from. The RSI network may be aclass-based network, in which case the nodes also share a common classdesignation representative of an asset class. For instance, theembodiment of the class-based networks described in U.S. Pat. No.6,745,027 and in application publication no. US 2005/0093703 A1, eachcomprises an RSI network when the data communications devices of thenodes include sensor-acquired information obtained from associatedsensors. The sensors may be temperature and humidity sensors, forexample, for detecting the temperature and humidity relative to an assetbeing tracked or monitored, with the sensor-acquired information beingcommunicated back to an application server upon acquisition of the databy the sensor or at a predetermined time, as desired. It is preferredthat the RSI network comprises an ad hoc class-based network.

In another aspect of the invention, an apparatus for determining aterrestrial location comprises a computer and a computer readable mediumaccessible by the computer. The computer readable medium includes datarepresentative of a master mapping of the sky relative to the surface ofthe Earth and computer-executable instructions for determining aterrestrial location based on data representative of a capturedearthbound image of the sky and an identified time at which theearthbound image was captured.

In a feature of this aspect, the computer determines the terrestriallocation by comparing the master mapping of the sky to the capturedearthbound image. In accordance with this feature, the terrestriallocation that is determined represents the terrestrial location fromwhich the earthbound image of the sky was captured at the identifiedtime.

In another feature of this aspect, the computer-executable instructionsdetermine the terrestrial location further based on data indicative ofmovement, including data indicative of magnitudes of acceleration anddeceleration, directions of acceleration and deceleration, and times ofacceleration and deceleration. The terrestrial location that isdetermined represents a projection of travel from a terrestrial locationfrom which the earthbound image of the sky was captured at theidentified time. In an additional feature, the computer is disposed inelectronic communication with a wide area network (WAN). In accordancewith this aspect, the computer comprises a network interface to acellular communications network. In another feature of this aspect, thecomputer comprises a network interface to a satellite communicationsnetwork. In yet another feature of this aspect, the computer comprises aserver that includes a network interface to the Internet.

In another aspect of the invention, a system comprises an apparatus thatis deployed in a generally known geographical region. The deployedapparatus includes an imaging component configured to capture anearthbound image of the sky from a terrestrial location, a chronometriccomponent that measures time synchronously with standard time, acommunication component configured to wirelessly transmit datarepresentative of a captured earthbound image of the sky, and acontroller. The controller is arranged in electronic communication withthe imaging component, the chronometric component, and the communicationcomponent. The controller is also configured to cause an earthboundimage of the sky to be captured using the imaging component at a timeidentified by the chronometric component and data representative of thecaptured earthbound image to be wirelessly transmitted. The systemfurther comprises an apparatus for determining a terrestrial location ofthe deployed apparatus within the generally known geographical regioncomprising a computer and a computer readable medium accessible by thecomputer. The computer readable medium includes data representative of amaster mapping of the sky relative to the surface of the Earth andcomputer-executable instructions for determining a terrestrial locationbased on the data wirelessly transmitted from the deployed apparatus andthe identified time at which the earthbound image was captured.

In a feature of this aspect, the system further comprises a plurality ofdeployed apparatus, each deployed apparatus including an imagingcomponent configured to capture an earthbound image of the sky from aterrestrial location, a chronometric component that measures timesynchronously with standard time, and a communication componentconfigured to wirelessly transmit data representative of a capturedearthbound image of the sky. The apparatus further includes a controllerthat is arranged in electronic communication with the imaging component,the chronometric component, and the communication component andconfigured to cause an earthbound image of the sky to be captured usingthe imaging component at a time identified by the chronometric componentand data representative of the captured earthbound image to bewirelessly transmitted.

In furtherance of this feature, the plurality of deployed apparatuscomprises sensors that are configured for monitoring of military troopmovement. In accordance with this feature, a sensor of at least onedeployed apparatus comprises a motion detector. With further regard tothis feature, a sensor of at least one deployed apparatus comprises amicrophone. In further accordance with this feature, a sensor of atleast one deployed apparatus comprises a video camera.

With further regard to this feature, each of the plurality of deployedapparatus captures a plurality of earthbound images at predeterminedtime intervals. In accordance with this feature, the plurality ofdeployed apparatus comprise triangulating sensors that are configured totriangulate the position of a transmitter. The computer-executableinstructions determine a terrestrial location of the transmitter basedon the triangulation by the triangulating sensors, and the terrestriallocation of each of the triangulating sensors is based on the datawirelessly transmitted from each triangulating sensor and the identifiedtime at which each earthbound image was captured. With regard to thisfeature, the plurality of deployed apparatus includes a globalpositioning system receiver.

In yet another aspect of the invention, a method for determining aterrestrial location of an apparatus that is deployed in a generallyknown geographical region comprises the steps of capturing, by theapparatus, an earthbound image of the sky from a terrestrial location atan identified time; communicating, by the apparatus, data representativeof the captured earthbound image of the sky; and determining theterrestrial location of the apparatus based on the data communicated bythe apparatus by comparing the captured earthbound image of the sky to amaster mapping of the sky relative to the surface of the Earth.

In a feature of this aspect, the data representative of the capturedearthbound image of the sky that is communicated by the apparatusincludes the identified time at which the earthbound image of the skywas captured. In another feature of this aspect, the method furthercomprises the initial step of deploying the apparatus within thegeographical region. The identified time at which the earthbound imageof the sky is captured is a time that is predetermined prior todeployment of the apparatus. In an additional feature, earthbound imagesof the sky are captured by the apparatus at predetermined timeintervals.

In yet another feature of this aspect, the method further comprisesprocessing the captured earthbound image of the sky prior tocommunicating the data representative of the captured earthbound imageof the sky. In accordance with this feature, the processing comprisescompensating for atmospheric distortions in the captured earthboundimage of the sky. In furtherance of this feature, processing comprisessharpening of the captured earthbound image of the sky.

In an additional feature, the capturing of an earthbound image of thesky comprises capturing the earthbound image of the sky along a verticalskyward axis local to the terrestrial location at which the image iscaptured. In yet another feature, the method further comprisesperforming correction calculations for the captured earthbound image ofthe sky when the earthbound image of the sky is not captured along alocal vertical skyward axis, whereby the data representative of thecaptured earthbound image of the sky corresponds to an earthbound imageof the sky that is captured along a vertical skyward axis local to theterrestrial location at which the image is captured. In accordance withthis feature, the correction calculations utilize an angle measuredbetween an axis of the captured earthbound image and the verticalskyward axis local to the terrestrial location at which the image iscaptured.

In another feature, the capturing of the earthbound image occurs atnight. In yet another feature, the capturing of the earthbound imageoccurs in daylight.

In an additional feature, the step of determining the terrestriallocation of the apparatus based on the data communicated by theapparatus by comparing the captured earthbound image of the sky to amaster mapping of the sky relative to the surface of the Earth includesmanipulating the master map of the sky into a model in which the shapeof a sphere is disposed above the surface of the Earth; projectinglatitude and longitude lines perpendicularly from the surface of theEarth onto the master mapping of the sky; comparing the capturedearthbound image to the manipulated master mapping of the sky; andmatching the captured earthbound image to the manipulated master mappingof the sky and reading the latitude and longitude values on themanipulated master map of the sky at the point where the capturedearthbound image most closely matches the manipulated master map of thesky, thereby determining the terrestrial location from which theearthbound image was captured by the deployed apparatus.

In another feature, the step of communicating, by the apparatus, datarepresentative of the captured earthbound image of the sky compriseswirelessly communicating, by the apparatus, the data representative ofthe captured earthbound image of the sky. In furtherance of thisfeature, the wireless communications comprise radio frequencycommunications.

In a further feature, the method further comprises communicating thedata representative of the captured earthbound image of the sky over awide area network (WAN). In another feature, the method furthercomprises communicating the data representative of the capturedearthbound image of the sky over a satellite communications network. Inyet another feature, the method further comprises communicating the datarepresentative of the captured earthbound image of the sky over acellular communications network. In an additional feature, the methodfurther comprises communicating the data representative of the capturedearthbound image of the sky over the Internet. In still yet anotherfeature, the method further comprises communicating the determinedterrestrial location of the apparatus to the apparatus.

In addition to the aforementioned aspects and features of the presentinvention, it should be noted that the present invention furtherincludes the various possible combinations of such aspects and features.

VI. BRIEF DESCRIPTION OF THE DRAWINGS

One or more embodiments of the present invention will be described indetail with reference to the accompanying drawings which are brieflydescribed below, and wherein the same elements are referred to with thesame reference numerals.

FIG. 1 is a block diagram illustrating a locator system in accordancewith a preferred embodiment of the present invention.

FIG. 2 is a block diagram illustrating the components and functioning ofthe communications device and the imaging device.

FIG. 3 is a schematic illustration depicting an exemplary set upconfiguration for a communications device and an imaging device.

FIG. 4 is a schematic illustration depicting the process of matchingcollected image data to the master mapping of the stars in the sky.

VII. DETAILED DESCRIPTION

As a preliminary matter, it will readily be understood by one havingordinary skill in the relevant art (“Ordinary Artisan”) that the presentinvention has broad utility and application. Furthermore, any embodimentdiscussed and identified as being “preferred” is considered to be partof a best mode contemplated for carrying out the present invention.Other embodiments also may be discussed for additional illustrativepurposes in providing a full and enabling disclosure of the presentinvention. Moreover, many embodiments, such as adaptations, variations,modifications, and equivalent arrangements, will be implicitly disclosedby the embodiments described herein and fall within the scope of thepresent invention.

Accordingly, while the present invention is described herein in detailin relation to one or more embodiments, it is to be understood that thisdisclosure is illustrative and exemplary of the present invention, andis made merely for the purposes of providing a full and enablingdisclosure of the present invention. The detailed disclosure herein ofone or more embodiments is not intended, nor is to be construed, tolimit the scope of patent protection afforded the present invention,which scope is to be defined by the claims and the equivalents thereof.It is not intended that the scope of patent protection afforded thepresent invention be defined by reading into any claim a limitationfound herein that does not explicitly appear in the claim itself.

Thus, for example, any sequence(s) and/or temporal order of steps ofvarious processes or methods that are described herein are illustrativeand not restrictive. Accordingly, it should be understood that, althoughsteps of various processes or methods may be shown and described asbeing in a sequence or temporal order, the steps of any such processesor methods are not limited to being carried out in any particularsequence or order, absent an indication otherwise. Indeed, the steps insuch processes or methods generally may be carried out in variousdifferent sequences and orders while still falling within the scope ofthe present invention. Accordingly, it is intended that the scope ofpatent protection afforded the present invention is to be defined by theappended claims rather than the description set forth herein.

Additionally, it is important to note that each term used herein refersto that which the Ordinary Artisan would understand such term to meanbased on the contextual use of such term herein. To the extent that themeaning of a term used herein—as understood by the Ordinary Artisanbased on the contextual use of such term—differs in any way from anyparticular dictionary definition of such term, it is intended that themeaning of the term as understood by the Ordinary Artisan shouldprevail.

Furthermore, it is important to note that, as used herein, “a” and “an”each generally denotes “at least one,” but does not exclude a pluralityunless the contextual use dictates otherwise. Thus, reference to “apicnic basket having an apple” describes “a picnic basket having atleast one apple” as well as “a picnic basket having apples.” Incontrast, reference to “a picnic basket having a single apple” describes“a picnic basket having only one apple.”

When used herein to join a list of items, “or” denotes “at least one ofthe items,” but does not exclude a plurality of items of the list. Thus,reference to “a picnic basket having cheese or crackers” describes “apicnic basket having cheese without crackers”, “a picnic basket havingcrackers without cheese”, and “a picnic basket having both cheese andcrackers.” Finally, when used herein to join a list of items, “and”denotes “all of the items of the list.” Thus, reference to “a picnicbasket having cheese and crackers” describes “a picnic basket havingcheese, wherein the picnic basket further has crackers,” as well asdescribes “a picnic basket having crackers, wherein the picnic basketfurther has cheese.”

Referring now to the drawings, one or more preferred embodiments of thepresent invention are next described. The following description of oneor more preferred embodiments is merely exemplary in nature and is notintended to limit the invention or uses.

FIG. 1 is a block diagram illustrating a locator system in accordancewith a preferred embodiment of the present invention. The locator system10 is able to determine a terrestrial location of a communicationsdevice 12 by utilizing celestial image data collected at the terrestriallocation or site of the communications device 12 and the basictechniques of celestial navigation. The locator system may be utilizedto determine the location of the communications device at a singleparticular instant of time and may also be used to track the location ofthe communications device over a particular period of time. The locatorsystem 10 preferably comprises a communications device 12 in the form ofa remote sensor interface in electronic communication with an imagingdevice 20; a gateway 14; a network interface 16; and a server 18.

FIG. 2 is a block diagram illustrating components and functioning of thecommunications device 12 and the imaging device 20. The imaging device20 is used to capture earthbound images of the sky including stars thatare in view of the communications device 12. Such images are used todetermine by the server 18 the terrestrial location of thecommunications device 12, as described in further detail below.

In a preferred embodiment, the imaging device 20 is a photosensitivecharge-coupled device (CCD). A CCD is a sensor used for recording imagescomprising an integrated circuit containing an array of linked, orcoupled, capacitors. CCD units commonly respond to 70% of incidentlight, as opposed to photographic film, which captures only about 2% ofincident light. As a result, CCD units are favored for use byastronomers. In a CCD, an image is projected by a lens on the capacitorarray, causing each capacitor of the array to accumulate an electriccharge proportional to the light intensity at that location. Atwo-dimensional array captures the whole image or a rectangular portionthereof. Once the array has been exposed to the image, a control circuitcauses each capacitor to transfer its contents to its neighboringcapacitor. The last capacitor in the array dumps its charge into anamplifier that converts such charge into a voltage. By repeating thisprocess, the control circuit converts the entire contents of the arrayto a varying voltage, which it samples, digitizes and stores in memory.Stored images can then be transferred to another device such as aprinter, a storage device, or a video display device.

Generally, CCD units vary in sensitivity to respective ranges of light.For example, a non-visible light unit can be used to collect imagesduring daylight hours. Electromagnetic radiation of wavelengths below2000 Angstroms (ultraviolet) and above 7000 Angstroms (infrared) can becollected to reduce or avoid daylight saturation from the visiblespectrum. In processing the images collected by the CCD, digital signalprocessing techniques such as homomorphic filtering can be used tosubtract out imaging distortions caused by sun light and terrestriallight. These functions can be performed at the communications device 12and/or at the server 18.

In a preferred embodiment, the communications device 12 includescircuitry for image control and processing, a transmission component ordevice for communication processing, and a database for data storage. Itis further preferred that the communications device 12 include achronometric component such as a real-time clock in order to identifythe time at which an earthbound image of the sky is captured. This maybe accomplished by time stamping each earthbound image that is collectedby the imaging device 20 so that precise times are determined forcollected images. The communications device 12 further may include anaccelerometer, a compass, and a light sensor. The accelerometer andcompass, in conjunction with the chronometric component, collect datathat aids in determining the terrestrial location of a mobilecommunications device 12 based on an earlier determined terrestriallocation. This is particularly useful when an image of the sky cannot becaptured due to environmental circumstances, such as weather. Also, inorder to manage power consumption, the communications device 12preferably utilizes “common designation” network technologies and“wake-up” technologies as disclosed in the references incorporatedherein.

The gateway 14 is a communications device that is disposed in directelectronic communication with a wide area network (WAN) via a networkinterface 16. Communication between the gateway 14 and WAN is preferablywireless. As such, the gateway 14 may include a cellular transceiver forcommunication via a cellular telephone network, a satellite transceiverfor communication via a satellite network, or combination thereof.

The server 18 is located at a relatively centralized location and ispreferably disposed in electronic communication with the WAN, wherebythe server 18 and the communications device 12 may communicate with oneanother via the gateway 14. In a preferred embodiment, the server 18includes an image matching algorithm and a database containing a mastermapping of the sky showing the stars in the sky in their respectivelocations. The image matching algorithm is used to compare the mastermapping of the sky to the data received from the communications device12 in order to determine the location of the communications device 12.

In the locator system 10, the data representative of a capturedearthbound image is stored at the communications device 12 forcommunicating to the server 18. The data representative of a capturedearthbound image may be communicated at predetermined time intervals, inresponse to the occurrence of predetermined events, and/or upon demandthrough an appropriate instructing that is received by thecommunications device 12. Furthermore, a plurality of capturedearthbound images may be communicated to the server 18 at the same timeor different times.

One or more data acquisition devices or sensors may be included with thecommunications device 12 or otherwise associated with the communicationsdevice 12 such that the communications device 12 is disposed inelectronic communication for receiving data from the associated sensor.The sensor-acquired data preferably is also stored for communicating tothe server 18. Moreover, this sensor-acquired data may be communicatedat predetermined time intervals, in response to the occurrence ofpredetermined events, and/or upon demand through an appropriateinstructing that is received by the communications device 12.Furthermore, the sensor-acquired data may be communicated in conjunctionwith the data representative of a captured earthbound image.

The communications device 12 may be attached to, or otherwise directlyassociated with, an asset. Moreover, the communications device 12 mayform a node of a “class-based” network, which networks are disclosed inthe references incorporated herein.

Communications from the communications device 12 to the server 18preferably are wireless and occur directly or indirectly through thegateway 14 that provides access to the WAN. In this respect, the gateway14 preferably includes a network interface capable of communicating, forexample, with a satellite communications network, a cellularcommunications network, or an Ethernet network. The gateway 14 also maywirelessly communicate with the communications device 12 throughradiofrequency communications within the ISM band or another band, asdesired or appropriate. The gateway 14 further may be located at a fixedposition or may be mobile. In this regard, the gateway 14 may be carriedon an airplane or ground vehicle and may only intermittently communicatewith the communications device 12, i.e., when within communicationsrange.

As thus will be appreciated, the gateway 14 represents the gatewaythrough which the communications device 12 sends communications to theWAN and, specifically, to the server 18 connected to the WAN. It willfurthermore be appreciated that the communications device 12 is utilizedto remotely collect data and transmit such data to the server 18 at amore centralized and known location.

In alternative preferred embodiments, the gateway 14 and server 18 maybe combined and the WAN eliminated from the system. In such embodiments,the gateway includes the server computer, application software, anddatabase representing the master mapping of the sky, whereby the serverfunctions are performed at the gateway 14. In such alternative preferredembodiment, the gateway 14 may be mobile, temporarily stationary at afixed location for a duration of time, or fixedly located at a locationfor an indefinite period of time.

In operation, celestial image data is collected at the communicationsdevice 12, and the collected image data is utilized to determine thelocation of the device 12. Specifically, the imaging device 20 collectsimage data at a particular location. FIG. 3 is a schematic illustrationdepicting an exemplary configuration for a communications device and animaging device. Each image is preferably taken along a local verticalskyward axis, that is, parallel to the gravitational pull of the earthat the location where the image is taken. Alternatively, the anglebetween the axis of each image is determined relative to the localvertical axis, such as by determination of the direction ofgravitational pull, and corrections are made for images that are notcollected along a local vertical axis.

The communications device 12 receives the image data collected by theimaging device 20. The communications device 12 can perform some portionor all of the processing of the image data depending on the capabilitiesof the communications device 12. For example, the communications devicecan extract different resolutions from the CCD imaging device. Suchprecision facilitates pinpointing the location of the communicationsdevice 12. In addition, the image data is time-stamped by thecommunications device 12 using the real-time clock. Accelerometer datamay also be collected by the communications device 12.

The image data and other associated data are then sent to the server 18via the gateway 14. The image matching algorithm of the server 18processes the master mapping of the sky and the data sent from thecommunications device to determine the location of the communicationsdevice. FIG. 4 is a schematic illustration depicting the process ofmatching collected image data to the master mapping of the stars in thesky.

More particularly, the server 18 manipulates the master mapping of thesky into the shape of a sphere disposed above the surface of the Earth,in the appropriate dimensions to model the location of the stars withrespect to the Earth. Then latitude and longitude lines are projectedperpendicularly from the surface of the earth onto the master mapping ofthe sky. Collected image and time-stamp data is compared to the mastermapping until a match is found. When the collected data is matched withthe master mapping, the latitude and longitude lines that have beenprojected onto the master mapping may be read to determine the locationat which the image was taken. Image processing techniques are utilizedin compensating for atmospheric distortions and sharpening of the imageto reduce light noise. Precision of the location determination isgoverned by the accuracy of the real-time clock that records the timeeach image is taken, resolution of the CCD, and precision of the mastermapping of the stars in the sky. U.S. Patent Application Publication No.2003/0156324 A1 contains further explanation regarding celestialnavigation and the techniques thereof. The disclosure of this patentapplication related to celestial navigation is hereby incorporatedherein by reference.

In addition, the positions, apparent sizes, and orientations of the sun,the moon, other celestial bodies, and horizons constitute furtherinformation optionally utilized in determining the location from whicheach image is taken.

Images can be taken intermittently and time-stamped, for example duringdark hours of the night, for determination of absolute locations atabsolute times. Location information for times between and beyond thetimes of the intermittently taken images can be determined by combiningtime-stamped absolute location information with relative movementinformation deduced from data collected from the accelerometer and thereal-time clock. Thus location tracking is possible whether or notcontinuous image collection is possible or practiced.

Generally, multiple communications devices are participants in awireless network. Some of these communications devices are at known ordeterminable locations. Such locatable communications devices may beused in determining locations of devices unable to collect skywardimages, such as devices that are indoors, devices that are under somesort of cover that occludes skyward views, and devices lackingimage-collecting capabilities. If multiple communications devices areutilized, relative directions of a particular device can be determined,and the location thereof can be triangulated or at least determinedwithin some finite range.

The locator system in accordance with one or more preferred embodimentsof the invention is particularly useful in situations involving mobilecommunications devices and in various weather conditions in whichintermittently collected, time-stamped celestial image data can becombined with accelerometer data in deducing asset positions and inconstructing time-position mappings revealing the movements of assets.

Implementations in accordance with one or more preferred embodiments ofthe invention provide many tactical and financial advantages. Forexample, costs are minimized by centralized data processing at theserver without distribution of the database of celestial information,including the master mapping of the stars in the sky, to thecommunications devices. In addition, on-demand imaging and locationdetermination promote long battery life. Further, the collection ofskyward images cannot be jammed by RF interference devices. Distributedprocessing prevents interception of position information. Navigationinformation can be gleaned from position, and knowledge of thesurroundings can be used to determine the status of a communicationsdevice.

Furthermore, implementations in accordance with one or more preferredembodiments of the invention have military advantages when used inhostile environments. For example, a mobile gateway may be located on anairplane that flies over a geographic region where communicationsdevices, e.g., sensors, have been deployed. The mobile gateway mayreceive location information transmitted from the communications deviceswhen the airplane flies over the geographical region in which thedevices are located. This method of receiving location transmissions isadvantageous, particularly in military applications, because if a rebelor insurgent (hereinafter “hostile”) is able to intercept thecommunications that are transmitted to the gateway by the sensors, theinformation used to identify the exact locations of the sensors will bein a form that is either extremely difficult to interpret or, morelikely, completely unusable to the hostile. In this respect, in order todetermine the location of the devices, a hostile would need the mastermapping of the sky and would need a computational system capable ofprocessing the complex computational algorithms involved in interpretingthe information from each sensor with respect to the master mapping ofthe sky. It is presumed that a hostile would not have such capabilities,and further presumed that a hostile would not have such capabilities inmobile form and/or readily disposable for use prior to the intercepteddata becoming stale. The method of determining exact terrestriallocations of the sensors in this implementation thus is advantageousover simply transmitting locational data derived from a GPS receiver ofa sensor, which may be more readily interpreted by a hostile.

Based on the foregoing description, it will be readily understood bythose persons skilled in the art that the present invention issusceptible of broad utility and application. Accordingly, while one ormore embodiments of the present invention have been described herein indetail, it is to be understood that this disclosure is only illustrativeand exemplary and is made merely for the purpose of providing a full andenabling disclosure of the invention. The foregoing disclosure is notintended to be construed to limit the present invention or otherwiseexclude any other embodiments, adaptations, variations, modifications orequivalent arrangements, the scope of the invention being limited onlyby the claims of an issued patent and the equivalents thereof.

1. A method for determining a terrestrial location of an apparatus thatis deployed in a generally known geographical region, comprising thesteps of: (a) capturing, by the apparatus, an earthbound image of thesky from a terrestrial location at an identified time; (b)communicating, by the apparatus, data representative of the capturedearthbound image of the sky; and (c) determining the terrestriallocation of the apparatus based on the data communicated by theapparatus by comparing the captured earthbound image of the sky to amaster mapping of the sky relative to the surface of the Earth; (d)wherein said determining step includes, (i) manipulating the master mapof the sky into a model in which the shape of a sphere is disposed abovethe surface of the Earth, (ii) projecting latitude and longitude linesperpendicularly from the surface of the Earth onto the master mapping ofthe sky, (iii) comparing the captured earthbound image to saidmanipulated master mapping of the sky, and (iv) matching said capturedearthbound image to said manipulated master mapping of the sky andreading the latitude and longitude values on said manipulated master mapof the sky at the point where said captured earthbound image mostclosely matches said manipulated master map of the sky, therebydetermining the terrestrial location from which the earthbound image wascaptured by the deployed apparatus.
 2. The method of claim 1, whereinthe data representative of the captured earthbound image of the sky thatis communicated by the apparatus includes the identified time at whichthe earthbound image of the sky was captured.
 3. The method of claim 1,wherein earthbound images of the sky are captured by the apparatus atpredetermined time intervals.
 4. The method of claim 1, furthercomprising processing said captured earthbound image of the sky prior tocommunicating the data representative of the captured earthbound imageof the sky.
 5. The method of claim 4, wherein the processing comprisescompensating for atmospheric distortions in the captured earthboundimage of the sky.
 6. The method of claim 4, wherein processing comprisessharpening of the captured earthbound image of the sky.
 7. The method ofclaim 1, wherein said capturing of an earthbound image of the skycomprises capturing the earthbound image of the sky along a verticalskyward axis local to the terrestrial location at which the image iscaptured.
 8. The method of claim 1, further comprising performingcorrection calculations for the captured earthbound image of the skywhen the earthbound image of the sky is not captured along a localvertical skyward axis, whereby the data representative of the capturedearthbound image of the sky corresponds to an earthbound image of thesky that is captured along a vertical skyward axis local to theterrestrial location at which the image is captured.
 9. The method ofclaim 8, wherein said correction calculations utilize an angle measuredbetween an axis of the captured earthbound image and the verticalskyward axis local to the terrestrial location at which the image iscaptured.
 10. The method of claim 1, wherein said capturing of theearthbound image occurs at night.
 11. The method of claim 1, whereinsaid capturing of the earthbound image occurs in daylight.
 12. A methodfor determining a terrestrial location of an apparatus that is deployedin a generally known geographical region, comprising the steps of: (a)deploying the apparatus within the geographical region; (b) capturing,by the apparatus, an earthbound image of the sky from a terrestriallocation at an identified time; (c) communicating, by the apparatus,data representative of the captured earthbound image of the sky; and (d)determining the terrestrial location of the apparatus based on the datacommunicated by the apparatus by comparing the captured earthbound imageof the sky to a master mapping of the sky relative to the surface of theEarth; (e) wherein the identified time at which the earthbound image ofthe sky is captured is a time that is predetermined prior to deploymentof the apparatus; and (f) wherein said step of determining theterrestrial location of the apparatus based on the data communicated bythe apparatus by comparing the captured earthbound image of the sky to amaster mapping of the sky relative to the surface of the Earth includes,(i) manipulating the master map of the sky into a model in which theshape of a sphere is disposed above the surface of the Earth; (ii)projecting latitude and longitude lines perpendicularly from the surfaceof the Earth onto the master mapping of the sky; (iii) comparing thecaptured earthbound image to said manipulated master mapping of the sky;and (iv) matching said captured earthbound image to said manipulatedmaster mapping of the sky and reading the latitude and longitude valueson said manipulated master map of the sky at the point where saidcaptured earthbound image most closely matches said manipulated mastermap of the sky, thereby determining the terrestrial location from whichthe earthbound image was captured by the deployed apparatus.
 13. Themethod of claim 1, wherein said step of communicating, by the apparatus,data representative of the captured earthbound image of the skycomprises wirelessly communicating, by the apparatus, the datarepresentative of the captured earthbound image of the sky.
 14. Themethod of claim 13, wherein the wireless communications comprise radiofrequency communications.
 15. The method of claim 1, further comprisingcommunicating the data representative of the captured earthbound imageof the sky over a wide area network (WAN).
 16. The method of claim 1,further comprising communicating the data representative of the capturedearthbound image of the sky over a satellite communications network. 17.The method of claim 1, further comprising communicating the datarepresentative of the captured earthbound image of the sky over acellular communications network.
 18. The method of claim 1, furthercomprising communicating the data representative of the capturedearthbound image of the sky over the Internet.